UPS systems are critical pieces of infrastructure. They provide round the clock autonomous vigilance against power failure. As UPS systems are in constant operation, with online units continuously converting and cleaning incoming electrical power this eventually takes a toll on even the most robust UPS systems.
Don’t be concerned, maintenance doesn’t have to cost the earth in most cases will be significantly cheaper than repairing or replacing the UPS unit if it fails. A well maintained UPS is much more likely to not experience a hardware failure than one that is. The most important thing is to ensure your UPS is ready and able to provide backup power.
At the heart of all UPS are a heap of batteries. The vast majority are sealed lead acid batteries. The type and configuration of batteries in each UPS varies greatly depending on the size.
The more sophisticated UPS systems (online UPS) typically use fans to assist in cooling power electronics. These fans have a MTBF (Mean Time Before Failure) which means they will inevitably fail.
Harder to diagnose capacitor failures can cause a lot of trouble, and can also inadvertently degrade the UPS batteries. In large UPS they are usually routinely replaced as part of a comprehensive maintenance program.